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In just four months in office, President Donald Trump has betrayed many of the Americans who believed his campaign promises. Last week, he betrayed the planet.

Trump’s foolish decision to pull out of the Paris climate change agreement — a pact endorsed by almost every other nation on Earth — is yet another sign that he is exceptionally unfit for the job.

The United States now joins Syria and Nicaragua as the only three nations in the world not party to the agreement. Nicaragua’s refusal to sign stems from the agreement not going far enough to fight the devastating effects of climate change. Even such forward-thinking leaders as Russia’s Vladimir Putin and North Korea’s Kim Jong Un signed the agreement, acknowledging the serious challenges facing the world as climate change accelerates.

The voluntary agreement of now 194 nations seeks to keep global average temperatures from rising 2 degrees Celsius by pledging to cut or limit emissions from burning fossil fuels. Nicaragua is right on one count: It does not go far enough. But it marked the first time the world community came together in an attempt to head off one of the most dangerous threats the planet has faced.

The office of president carries responsibility not only for the health of American people and environment, but for the world. In stepping away from the Paris accord, the president is abrogating that responsibility to appease a handful of fossil fuel lobbyists and the know-nothing climate change deniers he has installed in his administration. Even Secretary of State Rex Tillerson, the former CEO of ExxonMobil, favored staying in.

Trump has further cemented in the minds of Americans and others around the globe that he has no sense of moral responsibility to protect future generations from the ravages of climate change. He has set into motion a calamitous chain of events that could be irreversible. When will he wake up to the enormity of the consequences of continuing to spew carbon into the atmosphere — when the Atlantic Ocean rises to swallow up Mar-a-Lago?

Trump’s decision to make America a rogue nation on climate change, underscored by his Rose Garden speech insulting many of our long-held allies, is an outrage — but not that surprising. This is only the most recent step in Trump’s mad crusade to cripple efforts to protect the American people and the planet from industrial pollution.

The world watched as this president nominated climate change denier Scott Pruitt to lead the Environmental Protection Agency. Pruitt notoriously sued or supported lawsuits against the EPA more than two dozen times and disbanded Oklahoma’s environmental protection unit while he was the state’s attorney general.

Since Pruitt took the reins at EPA, the administration has rolled back rules to protect tap water for 117 million Americans. Pruitt personally overruled the agency’s own scientists to abort a scheduled ban on a dangerous pesticide that can harm children’s brains. With a straight face, he argued that his boss’s proposal to cut the budget for the Superfund program by 30 percent represented a stronger commitment to clean up the nation’s most severely polluted toxic waste sites.

Just last month, the administration appointed Nancy Beck to a high-level position in the Office of Chemical Safety and Pollution Prevention. Beck previously worked for the American Chemistry Council, the powerful lobby that represents ExxonMobil Chemical and Dow Chemical, among other big polluters, and for decades has fought efforts to protect Americans from hazardous substances in drinking water, food and consumer products.

But in pulling out of the Paris agreement, Trump not only showed his disregard for the nation’s health and safety but also for the planet’s future. In the eyes of the global community, he has given the United States a black eye that may take generations to heal.

Walking away from the climate pact is one of the most stunningly wrong-headed, uninformed decisions ever made by a president of the United States — the kind of bullheadedness seen from zealots who close their eyes to science and common sense. The evidence mounts daily that the Oval Office is occupied by exactly that kind of man.

Ken Cook is president of the Environmental Working Group. He wrote this for InsideSources.com.